The broad, long-term objective of this project is to develop a new class of drugs for treatment of multiple sclerosis (MS). The lead compound in the current proposal is VG1000, a minimal recombinant TCR ligand (RTL) containing MHC class II (1(1 domains of HLA-DR2 covalently linked to myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide. This unique construct has demonstrated potent therapeutic activity in DR2 transgenic (Tg) mice with MOG-35-55 peptide induced experimental autoimmune encephalomyelitis (EAE) through mechanisms that include partial agonist signaling and cytokine switching of targeted T cells that might contribute to CNS infiltration and myelin damage in MS. To further develop and test the efficacy of VG1000 in MS patients, it is here proposed to 1) scale up drug manufacture of sufficient quantities for pre-clinical and Phase I human clinical studies; 2) conclude pre-clinical safety studies, including maximum non-effective dose, maximum tolerated dose, and repeat dose toxicity studies; and 3) conduct Phase I clinical trials in accordance with FDA and NIH guidelines under an approved IND. For Aim 1, negotiations are underway with drug manufacturers to prepare large quantities of GMP grade VG1000 by fermentation of E. coil harboring multiple copies of a recombinant DNA plasmid from which the protein can be expressed, harvested and purified. The identity between the preclinical drug and the GMP drug for Phase I trials will be established through biophysical and biochemical parameters, and efficacy studies in DR2 transgenic mice with EAE. Furthermore a calcium mobilization bioassay using MOG-35-55 peptide-specific DR2 hybridoma cells will provide an in vitro standardized measure of drug potency. For Aim 2, it is proposed to determine the highest dose of VG1000 that does not produce a measurable clinical effect in DR2 mice with EAE in order to establish a starting dose for human clinical studies. Moreover, it is proposed to establish the maximum tolerated dose of VG1000 in DR2 Tg mice Using single injections ranging from 100 to 1,000 fgVG1000, and to evaluate repeat dose toxicity using injections of VG1000 ranging from 33 to 1,000f.g. For Aim 3, it is proposed to carry out a Phase I safety study using a starting dose of about 3mg/60kg, followed by a higher dose of15mg/60kg in two cohorts of 8 male and 8 female DR2+ MS patients prescreened for T cell responsiveness to MOG-35-55 peptide. Patients will be monitored for changes in clinical status, gadolinium enhancing lesions assessed by magnetic resonance imaging, T cell responses to MOG-35-55 peptide, and antibody response to drug. The proposed studies will address key milestones to establish clinical safety of VG1000 needed for subsequent proof-of-principle trials to evaluate inhibition of MOG-specific T cell responses and clinical efficacy. [unreadable] [unreadable]